Tachypleus gigas – The hoRRoR in relation to science

ByeverythingbugpicsPosted on

This is by far the worst bug story I have to tell so far, and I hope nothing is going to beat that one.

We found this couple of horseshoe crabs in the early morning. They were very calm and hardly moving. Obviously they were on the way back into the water, but with a lot of patience. Interestingly they did not just walk into the waves, but they pressed themselves down into the sand, I guess to avoid being washed up. And only if the tide was high enough, they would let go and swim. So the crab doesn’t go to the ocean, the ocean goes to the crab!

  • Deep in the sand
  • the smaller male behind
  • waiting for the water
  • there are legs

So where is it the hoRRoR? Here: The three Rs of science have been introduced by William Moy Stratton Russell and Rex L Burch in 1959, standing for replacement, reduction and refinement of the use of animals in science. Thinking of all animal testing done, it was surprising to me that it came up so early. Great!

Only 3 years earlier, in 1956, Fred Bang (!) from the US discovered, that bacterial endotoxins clog horseshoe crabs blood. That seems to be a special behavior.

How do these two facts come together? They do not really. In fact this lead me to the conclusion, that maybe the last 2 Rs (reduction and refinement) left too many options for us humans to not follow the first R, replacement. It is 2021 and we (still) make use of this special behavior of horseshoe crab-blood in large scale. Globally. No replacement.

Since the FDA approved the horseshoe crab blood as test medium for bacterial endotoxins in 1977, any device or substance that comes in contact with human blood will be tested. Estimated 20 million crabs have been caught and bled in the US since then. That’s only the number for the US.

You can find videos on YouTube (“horseshoe crab bleeding”). There is one cartoon version, what already indicates that is a bit rough, and there is also real videos of how the crabs are cleaned and bled before they get marked and released if they survived (to be bled the next year again). The numbers are for the US only, in China is the same situation (without data). There it seems to be common practice to process the bled crabs to food. 

The blood is blue by the way, the crabs look a lot like aliens, but still there is no doubt that we are the monsters in this scenery. It is horror!

There are 4 different species of horseshoe crabs, which actually aren’t crabs but more or less arachnids. Limulus polyphemus is the one in the US, from their blood Limulus amebocyte lysate (LAL) is produced. Our species and the one from China is used for the production of Tachypleus amebocyte lysate (TAL), basically the same, the difference is the first letter from the different genera (our T. gigas or T. tridentatus from China). The fourth species, the Mangrove horseshoe crab (Carcinoscorpius rotundicauda) is much smaller than the others, and mainly threatened by human consumption.

Only in the very few last years possible alternatives to LAL came up and will hopefully make their way to become the new standard test. 

Sure we absolutely need the best possible quality control for medical devices and substances. But how has it has been possible, that the entire world implemented a test, that is based on horseshoe crab bleeding? 

I’m sure most of us weren’t even aware. The abbreviation LAL does of course hide its cruel origin, and if you don’t know what a lysate is, you wouldn’t suspect anything from the full name. Lysate is just homogenized blood, with shredded blood cells. LAL and TAL is processed horseshoe crab blood.

Here is the list of protected species in Singapore. Horseshoe crabs are not on the list though they are endangered. In fact only very few species are officially protected. That should not stop us to to protect animals ourselves, at least by not catching or even consuming wild animals!

This page here has all the other fascinating details about horseshoe crabs, the hoRRoRed aliens.Â